The purpose of this project is to measure the extent of the problem of chronic, severe and disabling headaches, the impact of headache disorders on society, and the headache population. In addition, it is planned to examine the present usage of health care by the headache population and to identify etiological and environmental factors which may be associated with various types of headache. The survey questionnaire which includes sections on demography, medical information and history, cost, work and financial loss, etc., is currently under development. A validaton study of the questionnaire and the algorithm for identification of major types of headaches are also being designed.